TW201930190A - Activated carbon, metal-carrying activated carbon using same and hydrogenation reaction catalyst - Google Patents

Abstract

The present invention pertains to an activated carbon, which shows an electric conductivity of 3.5 s/cm or greater when determined by the powder resistance measurement method under a load of 12 kN and has an oxygen content of 3.0 mass% or greater, a metal-carrying activated carbon using the same, etc.

Description

   Activated carbon, metal-loaded activated carbon using the same, and hydrogenation catalyst   

The present invention relates to a catalyst-containing activated carbon and a metal-loaded activated carbon using the same.

Catalytic hydrogenation using heterogeneous catalysts is one of the important processes in the chemical industry and is widely used in industry. In addition, catalysts that carry metal catalysts such as precious metals on carbon materials such as activated carbon are widely used in industrial processes such as hydrogenation reactions and dehydrogenation reactions.

The carbon material used in the catalyst carrier is often subjected to oxidation treatment in order to improve the reaction efficiency such as hydrogenation reaction caused by the micronization of the supported metal catalyst. For example, Patent Document 1 describes that activated carbon is preliminarily subjected to a heat treatment (oxidation treatment) at 300 to 500 ° C, and then an ion exchange method is performed to form surface functional groups and carry a catalyst (metal). Micronization to improve catalyst reaction efficiency.

However, there is a limit to the atomization of a metal catalyst using an oxidation treatment as described in Patent Document 1, and the performance of the obtained catalyst is not satisfactory. In addition, in the improvement of catalyst performance, it is also important to increase the specific surface area of carbon materials, but there is a limit to increasing the specific surface area. In addition, by increasing the specific surface area, the cost also increases. Therefore, it is also desirable to improve the reaction efficiency by adjusting physical properties other than the specific surface area.

    [Prior technical literature]         [Patent Literature]    

Patent Document 1: Japanese Unexamined Patent Publication No. 6-269667

[Invention Summary]

One aspect of the activated carbon of the present invention is characterized in that the conductivity obtained by powder resistance measurement due to a load of 12 kN is 3.5 S / cm or more, and the oxygen content is 3.0% by mass or more.

    [Form of Implementing Invention]    

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide an activated carbon for a catalyst carrier and a carrier using the same, which has the same degree of micronization of the metal as the past, and at the same time improves the specific surface area and the catalyst performance. There is metal activated carbon.

As a result of repeated detailed investigations by the inventors of the present invention in order to solve the above-mentioned problems, it was found that the above-mentioned problems can be solved by the following configuration, and further repeated discussions based on this knowledge have led to completion of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. In addition, the scope of the present invention is not limited to the embodiments described herein, and various changes can be made without departing from the scope of the present invention.

    [Activated carbon]    

The activated carbon according to this embodiment is characterized in that the conductivity obtained by powder resistance measurement at a load of 12 kN is 3.5 S / cm or more, and the oxygen content is 3.0% by mass or more.

The activated carbon of this embodiment can exhibit very excellent catalyst performance according to the above-mentioned configuration. By using the activated carbon of the present invention as a carrier for a metal catalyst, the micronization of the metal is the same as in the past, and at the same time, the specific surface area is increased, and the catalyst performance can be improved. That is, according to the present invention, it is possible to provide a catalyst-loaded activated carbon that has excellent catalyst performance while suppressing costs.

The electrical conductivity of the activated carbon of this embodiment is 3.5 S / cm or more as described above. By setting the conductivity within the above range, it is estimated that the interaction between the metal catalyst and activated carbon described later changes, and the catalyst performance is improved. A more preferable electrical conductivity is 5.0 S / cm or more, and a still more preferable 6.0 S / cm or more.

On the other hand, in the activated carbon of this embodiment, the upper limit of the electrical conductivity is not particularly limited, but if it becomes too large, the carbon structure will be excessively developed, so that the activation treatment will take time, which is economically unfavorable. If the electrical conductivity is too high, the oxidation treatment may become difficult. In this case, the degree of dispersion of the metal catalyst is lowered, which is not preferable. Therefore, the electrical conductivity of the activated carbon of this embodiment is preferably 15 S / cm or less, more preferably 13 S / cm or less, and still more preferably 10 S / cm or less.

In this embodiment, "conductivity" means the conductivity obtained by powder resistance measurement at a load of 12 kN in activated carbon that is pulverized to a predetermined particle size (particle size distribution). In the measurement of the electrical conductivity, the particle diameter of the measurement sample has a great influence. Therefore, specifically, it can be measured by a measurement method described in Examples described later.

The oxygen content of the activated carbon in this embodiment is 3.0% by mass or more. When the oxygen content is 3.0% by mass or more, the degree of dispersion of the metal catalyst is sufficiently obtained (the particle size of the metal catalyst becomes sufficient), and the reaction efficiency of the hydrogenation reaction is improved. A more preferable oxygen content is 4.0 mass% or more, and a further more preferable 5.0 mass% or more.

On the other hand, in the activated carbon of this embodiment, the upper limit of the oxygen content is not particularly limited, but if it becomes too large, carbon consumption increases and the yield of activated carbon decreases, so from an economic point of view, Not good. Moreover, when the said oxygen content is too much, the hardness of activated carbon will fall, and the metal carried by a powder will fall off, and it is inferior from this viewpoint. Therefore, the oxygen content of the activated carbon of the present invention is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, and even more preferably 10.0% by mass or less.

In the present embodiment, the "oxygen content" means the amount of oxygen in the activated carbon that is pulverized and dried, and specifically, it can be measured by a measurement method described in Examples described later.

The B ET specific surface area of the activated carbon in this embodiment is not particularly limited, but is preferably 1,000 m ² / g or more, more preferably 1300 m ² / g or more, and still more preferably 1600 m ² / g or more. When the BET specific surface area is 1000 m ² / g or more, the adsorption of the reaction compound is sufficiently obtained, and the reaction efficiency of the hydrogenation reaction is improved. On the other hand, in the activated carbon of this embodiment, the upper limit of the BET specific surface area is not particularly limited, but if it becomes too large, the yield of the obtained activated carbon decreases, and therefore it is less economical. good. Thus, the activated carbon of the present invention, the BET specific surface area, preferably 2200m ² / g or less, more preferably 2100m ² / g or less, further more preferably 2000m ² / g or less.

In this embodiment, the specific surface area means a BET specific surface area calculated by a nitrogen adsorption method. The measurement method of the specific surface area can be measured by a known method, and examples thereof include a method of performing a nitrogen adsorption isotherm measurement and a calculation from the obtained adsorption isotherm. More specifically, it can measure by the method described in an Example.

The average pore diameter of the micropores of the activated carbon in this embodiment is not particularly limited, but is preferably 1.55 nm or more, more preferably 1.60 nm or more, and even more preferably 1.65 nm or more. If the average pore diameter of the micropores is 1.55 nm or more, the diffusion in the catalyst particles of the reaction compound is improved, and the hydrogenation reaction is efficient. On the other hand, in the activated carbon of this embodiment, the upper limit of the average pore diameter of the micropores is not particularly limited, but if it becomes too large, the yield of the obtained activated carbon decreases, so from an economic point of view, Less good. Therefore, the average pore diameter of the micropores of the activated carbon of the present invention is preferably 1.90 nm or less, more preferably 1.85 nm or less, and even more preferably 1.80 nm or less.

In this embodiment, the average pore diameter of the micropores is calculated by a nitrogen adsorption method, and can be measured by a known method. Specific measurement methods include, for example, a method of performing a nitrogen adsorption isotherm measurement and a calculation from the obtained adsorption isotherm. More specifically, it can measure by the method described in an Example.

In this embodiment, the shape of the activated carbon is not particularly limited, but it is preferably any of granular, powdery, fibrous, pelletized, and spherical shapes. The shape of the activated carbon can be appropriately selected according to the application, but it is usually granular or powdery, and particularly preferably a powdery powder having high performance per volume.

For the pulverization, for example, a jaw crusher, a hammer crusher, a pin mill, a roll mill, a rod mill, a ball mill, and a jet mill can be used.

In this embodiment, the size and granularity of the activated carbon are preferably about 150 μm to 5 mm, and the average particle size (D50) is about 1 to 100 μm. .

In this embodiment, the value of D50 is a value measured by a laser diffraction measurement method in the same manner as in the examples described later. For example, the value is measured by a wet-type particle size distribution measuring device (Microtrac, manufactured by Nikkiso Co., Ltd.). MT3300EX II).

    [Manufacturing method of activated carbon]    

As described above, the activated carbon of this embodiment can be heat-treated at a temperature of 1100 ° C or higher by carbonizing the carbonaceous material, and then activated in a mixed gas environment containing water vapor, nitrogen, and carbon dioxide. It is obtained by performing an oxidation treatment in an oxidizing environment. That is, the present invention also includes a method for producing activated carbon, which includes at least a step of heat-treating a carbonized material of carbonaceous material at a temperature of 1100 ° C or higher, an activation treatment step, and an oxidation treatment step.

    (Carbon material)    

The carbon material may be selected from all known materials, and examples thereof include plants (coconut shell, rice husk, coffee bean residue, wood, etc.), natural polymers (starch, cellulose, lignin, etc.), semi-synthetic Polymers (cellulose esters, cellulose ethers, lignin resins, etc.), synthetic polymers (phenol resins, furan resins, epoxy resins, etc.), natural minerals, etc. These raw materials can be used individually or in combination of 2 or more types. The preferred raw materials are plant materials such as wood, and more preferably coconut shells with few impurities.

The coconut used as the raw material of the coconut shell is not particularly limited, and examples thereof include oil palm (oil coconut), coconut palm, snake skin, and sea coconut. The coconut shells obtained from such coconuts may be used alone or in combination of two or more kinds. Among them, because it is easy to obtain and has a low price, it is particularly suitable for use as food, detergent raw materials, biodiesel oil raw materials, etc., and is a large amount of biomass waste derived from coconut palm or oil palm. Coconut shell.

The calcinable coconut shell is preferably obtained in the form of charcoal (coconut shell charcoal) and used as a raw material. Here, charcoal generally refers to a solid that does not melt and soften and generates carbon-rich powders when heating coal, but also refers to heating organic materials that do not melt and soften and produce carbon-rich powders. s solid type. The method for producing charcoal from coconut shell is not particularly limited, and it can be produced by a method known in the art. For example, the coconut shell that is to be used as a raw material is, for example, an inert gas such as nitrogen, carbon dioxide, helium, argon, carbon monoxide, or a fuel exhaust gas, a mixed gas of these inert gases, or the inert gas as a main component. It can be calcined (carbonized) at a temperature of about 400 to 800 ° C under the environment of a mixed gas of other gases to produce a carbonized material dry distillation product.

    (Heat treatment step)    

The heat treatment of the dry distillation product can be performed by heating the dry distillation product, blocking oxygen or air, at a temperature of 1100 ° C or higher, preferably 1200 ° C or higher. If the heat treatment temperature is too low, the conductivity of the activated carbon becomes low, the interaction between the metal catalyst and the activated carbon becomes insufficient, and the catalyst performance decreases. In addition, the higher the heat treatment temperature, the higher the conductivity of the activated carbon. However, since the activation time for obtaining a sufficient specific surface area becomes longer, the manufacturing cost increases, which is not preferable. Therefore, the upper limit of the heat treatment temperature is preferably 1500 ° C or lower.

In addition, the means of heating is not specifically limited, For example, it can be performed using an electric furnace or the like.

    (Activation step)    

The activation treatment can be performed by a general method in the technical field to which the present invention pertains, and mainly includes two types of treatment methods, gas activation treatment and chemical activation treatment.

As the gas activation treatment, for example, a method of heating an activated carbon precursor in the presence of water vapor, carbon dioxide, air, oxygen, a combustion gas, or a mixed gas thereof is known. In addition, as the agent activation treatment, for example, it is known to mix an activator such as zinc chloride, calcium chloride, phosphoric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, magnesium hydroxide, and calcium hydroxide with an activated carbon precursor, and Method of heating in an inert gas environment. In this embodiment, a step of removing the remaining medicament is required for the activation of the medicament, and the manufacturing method becomes complicated. Therefore, it is preferable to use a gas activation treatment.

Gas activation treatment can use fluidized bed, multi-stage furnace, rotary furnace, etc., at a temperature above 850 ° C, preferably 850 ~ 1000 ° C (for example, 850 ~ 950 ° C), in the environment of a mixture of water vapor, nitrogen and carbon dioxide Carry on. By activating under the environment of the aforementioned mixture, the carbonized product is partially gasified to obtain activated carbon. Furthermore, the gas (a mixture of water vapor, nitrogen, and carbon dioxide) used to vaporize a portion of the carbonized material carbon dioxide can also be used to make natural gas, petroleum, or other flammable hydrocarbons. It is obtained by burning materials. In addition, the activation temperature usually varies within a range of about ± 25 ° C.

The activation time is not particularly limited, but may be 0.5 to 48 hours, preferably 1 to 24 hours, and more preferably 2 to 20 hours (for example, 6 to 12 hours). If the activation time is too short, a sufficient specific surface area cannot be obtained, and the catalyst performance after carrying a metal is reduced, and if it is too long, the productivity may be reduced.

The gas partial pressure is also not particularly limited. The water vapor partial pressure is 7.5 to 40%, preferably 10 to 30% (for example, 10 to 20%), and the carbon dioxide partial pressure is 10 to 50%, preferably 15 to 45% (for example, , 20 ~ 40%), nitrogen partial pressure 30 ~ 80%, preferably 40 ~ 70% (for example, 45 ~ 65%), gas partial pressure can also be water vapor partial pressure 10 ~ 40%, carbon dioxide fraction Pressure is about 10 ~ 40% and nitrogen partial pressure is about 40 ~ 80%. The total pressure of the gas is usually 1 atmosphere (about 0.1 MPa).

The total gas supply amount (flow rate) is not particularly limited, but is about 1 to 50 L / min, preferably about 1 to 25 L / min, relative to 100 g of the dry distillation raw material.

    (Acid cleaning step)    

The step of producing activated carbon according to the present embodiment may include an acid cleaning step. The acid cleaning step is a step of cleaning the activated carbon after the activation treatment with a cleaning solution containing an acid to remove impurities such as metal components contained in the activated carbon. The acid cleaning can be performed, for example, by immersing raw material activated carbon in a cleaning solution containing an acid. In the acid cleaning step, the raw material activated carbon may be washed with hydrochloric acid and then washed with water, and the acid washing and water washing may be repeated in appropriate combinations such as water washing and acid washing.

As the acid cleaning solution, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, formic acid, acetic acid, propionic acid, oxalic acid, tartaric acid, and citric acid, and saturated organic acids such as benzoic acid, and terephthalic acid, and other organic acids are preferably used. Among them, washing with hydrochloric acid is more preferable. When hydrochloric acid is used as the acid cleaning solution, the concentration of hydrochloric acid is preferably 0.1 to 3.0% by mass, and more preferably 0.3 to 1.0% by mass. If the concentration of hydrochloric acid is too low, it is necessary to increase the number of picklings in order to remove impurities. On the other hand, if the concentration of hydrochloric acid is too high, the remaining hydrochloric acid will increase. Therefore, by setting the concentration in the above range, the acid washing step can be efficiently performed. From the viewpoint of productivity, it is better.

The temperature of the liquid when pickling or washing is not particularly limited, but is preferably 0 to 98 ° C, more preferably 10 to 95 ° C, and even more preferably 15 to 90 ° C. If the temperature of the cleaning liquid when the raw material activated carbon is immersed is within the above-mentioned range, it is possible to carry out cleaning in which the load on the device is suppressed in a practical time, which is preferable.

    (Oxidation treatment step)    

The method for producing activated carbon according to this embodiment includes an oxidation treatment step. The oxidation treatment step is a step of oxidizing the activated carbon in an oxidizing environment to increase the oxygen content of the activated carbon. Specific examples include a method of performing heat treatment in a mixed gas environment containing oxygen, or a method of treating with an oxidizing agent such as hydrogen peroxide water, nitric acid, and potassium permanganate.

The oxidation treatment using oxygen can be performed using a fluidized bed, a multi-stage furnace, a rotary furnace, or the like, as in the activation treatment, and can be performed at a temperature of 400 ° C or higher, preferably 400 to 600 ° C. If the oxidation treatment temperature is less than 400 ° C, the oxidation of the activated carbon cannot be sufficiently performed, and above 600 ° C, the oxidation of the activated carbon proceeds rapidly, the carbon consumption becomes intense, and the yield decreases, which is not good.

The oxidation treatment time is not particularly limited, but may be 0.1 to 3 hours, preferably 0.2 to 2 hours, and more preferably 0.3 to 1 hour. If the oxidation treatment time is too short, the oxidation of the activated carbon cannot proceed sufficiently, and if it is too long, the productivity decreases.

The gas partial pressure is not particularly limited, and may be an oxygen partial pressure of 1 to 15%, a water vapor partial pressure of 5 to 15%, a carbon dioxide partial pressure of 5 to 15%, and a nitrogen partial pressure of about 50 to 80%. The total pressure of the gas is usually 1 atmosphere (about 0.1 MPa).

The total gas supply amount (flow rate) is not particularly limited, but it is about 1 to 100 L / min, and preferably about 1 to 50 L / min, with respect to 50 g of the activated product raw material.

    [Metal-laden activated carbon]    

The metal-supported activated carbon of this embodiment is characterized in that the metal serving as a catalyst is supported on the activated carbon as described above.

The metal to be carried is not particularly limited, and examples thereof include metals used as a catalyst for a hydrogenation reaction or a dehydrogenation reaction. Specific examples include palladium, platinum, ruthenium, rhodium, osmium, iridium, nickel, cobalt, osmium, vanadium, tungsten, molybdenum, iron, titanium, and the like, and more preferably a platinum group element (palladium, platinum, ruthenium) , Rhodium, osmium, iridium) or nickel, iron, among which palladium or platinum is suitable. These can be used alone or in combination.

The loading amount of the metal in the metal-supported activated carbon in this embodiment is not particularly limited, but it is preferably set to 0.1 to 50% by mass, and particularly preferably set to 0.5 to 10% by mass.

The metal-supported activated carbon of this embodiment can be prepared by a known method. For example, it can be manufactured by a method in which a precursor of a metal serving as a catalyst is adsorbed on the activated carbon as described above and then subjected to a reduction treatment.

Examples of the precursor of the metal (metal component) that can be used in the metal-supported activated carbon of this embodiment include, for example, metal chlorides, bromides, fluorides, hydroxides, nitrates, acetates, Carbonate, sulfate, ammonium salt, etc. can be used alone, or two or more of them can be used in an arbitrary ratio. Examples of the precursor of the palladium catalyst include palladium chloride, palladium nitrate, and palladium acetate.

As a method for adsorbing a metal precursor on activated carbon, for example, (i) an impregnation method in which activated carbon is suspended in a precursor solution of a metal component and then the solvent is distilled off, and (ii) the activated carbon is suspended in the foregoing The precursor solution is contacted with a precipitant to cause precipitation of metal hydroxides and the like on the surface of activated carbon, (iii) an ion exchange method for ion-exchanging metal ions at the acid or base point of the activated carbon, and (iv) Spray method in which the precursor solution is impregnated in a reduced pressure state, (v) After the activated carbon is exhausted, the precursor solution is added in small amounts one by one, and the initial wet method is impregnated with the same volume fraction of pore volume of the activated carbon )Wait. From the viewpoint of dispersibility and workability of metal components, among these, an impregnation method, a precipitation method, and an ion exchange method are preferred, and an impregnation method and a precipitation method are more preferred. There is no particular limitation on the adsorption order when a plurality of metal component precursors are adsorbed on activated carbon, and the precursors of the metal components may be adsorbed simultaneously, or the precursors of the respective components may be adsorbed individually.

After the precursor of the metal component is adsorbed on the activated carbon, a reduction treatment is performed to obtain a metal-supported activated carbon. The reduction treatment method is not limited to any liquid phase method or gas phase method, but is preferably a liquid phase method. Examples of the reducing agent used include hydrogen, formaldehyde, methanol, sodium borohydride, and hydrazine. The solvent is preferably water, and other solvents mixed with water may be used in combination. The reduction temperature is preferably from room temperature to 100 ° C.

As the metal-supported activated carbon of this embodiment, a hydrogenation reaction catalyst can be suitably used. The method for performing the hydrogenation reaction using the metal-supported activated carbon of this embodiment is not particularly limited, as long as the object (reaction matrix) is brought into contact with the hydrogen source and the metal-supported activated carbon, the object causes A hydrogenation reaction or a dehydrogenation reaction is sufficient.

Examples of the hydrogen source include reducing gases such as hydrogen; alcohols such as methanol, ethanol, and propanol; hydrazines such as hydrazine, methylhydrazine, allylhydrazine, and phenylhydrazine; and derivatives thereof and salts thereof. Among these hydrogen sources, hydrogen is preferably used.

The amount of the hydrogen source used is preferably 10 to 2000 moles per mole of the object (reaction matrix).

In the hydrogenation reaction, the used amount of the metal-supported activated carbon in this embodiment is, for example, preferably 1 mol relative to the object (reaction substrate), and the amount of the metal supported is 0.0001 to 1 mol.

The metal-supported activated carbon of this embodiment is very useful as a catalyst for a hydrogenation reaction, and therefore exhibits excellent effects in various industrial processes.

In this specification, various techniques are disclosed as described above, and the main techniques are summarized below.

That is, the activated carbon according to one aspect of the present invention is characterized in that the conductivity obtained by powder resistance measurement at a load of 12 kN is 3.5 S / cm or more, and the oxygen content is 3.0% by mass or more.

According to the structure described above, it is possible to provide an activated carbon having excellent catalyst performance.

The activated carbon is preferably derived from coconut shell. According to the foregoing, the above-mentioned effects can be more surely obtained.

Furthermore, in another aspect of the present invention, a metal-supported activated carbon is characterized in that a metal is supported on the activated carbon. According to the structure as described above, it is possible to provide a metal-supported activated carbon having excellent catalyst performance.

In the metal-supported activated carbon, the metal is preferably palladium. According to the foregoing, the above-mentioned effects can be more surely obtained.

The above-mentioned metal-supported activated carbon can further exhibit its effects by being used in a hydrogenation reaction catalyst.

    [Example]    

Hereinafter, the present invention will be described in more detail based on examples, but the following examples are not limited to the present invention.

First, an evaluation method for the characteristics of each activated carbon will be described.

    [Determination of Electrical Conductivity of Activated Carbon]    

The powder resistivity measurement unit "MCP-PD51" manufactured by Mitsubishi Chemical Analytech was used to measure the electrical conductivity of the activated carbon. The measurement of the electrical conductivity greatly affects the particle size of the measurement sample, so it is pulverized to make the 10% particle size (D10) of the cumulative distribution of activated carbon volume about 1 to 3 μm, and the 50% of the cumulative distribution of volume basis. The diameter (D50) is about 5 to 8 μm, the 90% particle size (D90) of the volume-based cumulative distribution is about 10 to 20 μm, and the electrical conductivity of the activated carbon pellets when a 12 kN load is applied is measured. The particle size of the pulverized activated carbon was measured by a laser diffraction measurement method. That is, the activated carbon to be measured is added to ion-exchanged water together with a surfactant to give ultrasonic vibration to prepare a uniform dispersion, and the measurement is performed using Microtrac MT3300EX-II manufactured by MicrotracBEL. The surfactant is "polyoxyethylene (10) octylphenyl ether" manufactured by Wako Pure Chemical Industries, Ltd. The analysis conditions are shown below.

    (Analysis conditions)    

Measurement times: 3 times

Measurement time: 30 seconds

Distribution display: Volume

Particle size classification: standard

Calculation mode: MT3000II

Solvent name: WATER

Upper measurement limit: 2000 μm, lower measurement limit: 0.021 μm

Residual ratio: 0.00

Pass score: 0.00

Residual ratio setting: invalid

Particle permeability: absorption

Particle refractive index: N / A

Particle shape: N / A

Solvent refractive index: 1.333

DV value: 0.0100 ~ 0.0500

Transmittance (TR): 0.750 ~ 0.920

    [Determination of the oxygen content of activated carbon]    

After the pulverized activated carbon was vacuum-dried at 120 ° C for 2 hours, Vario EL III manufactured by ELEMENTAR was used, and benzoic acid was used as a reference substance to measure the oxygen content of the activated carbon.

    [Determination of specific surface area of activated carbon]    

Using BELSORP-max manufactured by MicrotracBEL, the sample was activated carbon, heated under nitrogen flow (nitrogen flow rate: 50 mL / min) at 300 ° C for 3 hours, and the nitrogen adsorption and desorption isothermal of the activated carbon in 77K was measured line. The obtained from the adsorption-desorption isotherms, the BET equation by analyzing the multi-point method using, obtained by the curve of the opposite pressure P / P ₀ = 0.01 to 0.1 linear range of the specific surface area was calculated.

    [Determination of average pore diameter of micropores of activated carbon]    

The nitrogen adsorption and desorption isotherm obtained according to the above-mentioned method for measuring the specific surface area of activated carbon was analyzed by the MP method, and from the obtained micropore pore volume and micropore specific surface area, the average micropore pore diameter was calculated according to the following formula. .

D = 4000 × V / S

(In the formula, D represents the average micropore diameter (nm), V represents the micropore volume (mL / g), and S represents the micropore specific surface area (m ² / g))

    [Determination of benzene adsorption performance of activated carbon]    

According to the activated carbon test method JISK1474 (1991) in Japanese Industrial Standards, the benzene adsorption performance of activated carbon after activation treatment was measured. At 25 ° C, air containing a solvent vapor which is 1/10 of the saturated concentration of the solvent was flowed through the granular sample, and the equilibrium adsorption performance was obtained from the increase of the sample when the mass became constant.

    (Example 1)    

100 g of coconut shell charcoal was put into the furnace, air was blocked, and heat treatment was performed at 1300 ° C. Thereafter, 80 g of the heat-treated product was put into the flow furnace, and a mixed gas having a partial pressure of water vapor of 15%, a partial pressure of carbon dioxide of 11%, and a partial pressure of nitrogen of 74% was supplied to the furnace at a total pressure of 1 atmosphere and a flow rate of 20 L / min. Under the condition of activation temperature of 950 ° C, the activation time was adjusted so that the benzene adsorption performance became 21.8%, and the activation treatment was performed. Next, the activated product was acid-washed with hydrochloric acid (concentration: 1N, diluent: ion-exchanged water) at a temperature of 70 ° C for 30 minutes. In order to remove the residual acid, the ion-exchanged water was sufficiently washed and dried to obtain an acid. Clean activated carbon. Next, the acid-washed activated carbon was put into a flow furnace having a furnace temperature of 500 ° C, and a mixed gas having an oxygen partial pressure of 7%, a water vapor partial pressure of 11%, a carbon dioxide partial pressure of 8%, and a nitrogen partial pressure of 74% was introduced. The gas was supplied into the furnace at a total pressure of 1 atmosphere and a flow rate of 30 L / min, and the temperature of the heat treatment was raised to 550 ° C, and the oxidation treatment was performed until the yield became 90% to obtain activated carbon. The specific surface area, electrical conductivity, and oxygen content (O content) of the obtained activated carbon are shown in Table 1.

    (Example 2)    

Activated carbon was produced in the same manner as in Example 1 except that the activated benzene adsorption performance was adjusted to 30.9% after the activation time was adjusted. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Example 3)    

Activated carbon was prepared in the same manner as in Example 1 except that the activated benzene adsorption performance was adjusted to 45.0% after the activation time was adjusted. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Example 4)    

Activated carbon was produced in the same manner as in Example 1 except that the activated benzene adsorption performance was adjusted to 59.6% after activation time was adjusted. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Example 5)    

Activated carbon was produced in the same manner as in Example 1 except that the heat treatment temperature of coconut shell char was 1200 ° C., and the activation time was adjusted so that the benzene adsorption performance after activation became 31.1%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Example 6)    

Activated carbon was produced in the same manner as in Example 1 except that the heat treatment temperature of coconut shell char was 1100 ° C, and the activation time was adjusted so that the benzene adsorption performance after activation became 29.9%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Example 7)    

Activated carbon was produced in the same manner as in Example 1 except that the activated benzene adsorption performance was adjusted to 30.9% and the oxidation treatment was performed until the yield was 95.4%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Comparative example 1)    

Activated carbon was prepared in the same manner as in Example 1 except that the coconut shell char was not heat-treated and was put into the furnace, and the activation time was adjusted so that the activated benzene adsorption performance became 21.2%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Comparative example 2)    

Activated carbon was produced in the same manner as in Example 1 except that the coconut shell char was not heat-treated and was put into the furnace, and the activation time was adjusted so that the activated benzene adsorption performance became 31.6%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Comparative example 3)    

Activated carbon was produced in the same manner as in Example 1 except that the coconut shell char was put into the furnace without heat treatment and the activation time was adjusted so that the activated benzene adsorption performance became 46.0%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Comparative Example 4)    

Activated carbon was produced in the same manner as in Example 1 except that the coconut shell char was not heat-treated and was put into the furnace, and the activation time was adjusted so that the activated benzene adsorption performance became 60.9%. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

    (Comparative example 5)    

Activated carbon was produced in the same manner as in Example 1 except that the activated benzene adsorption performance was adjusted to 31.0% after activation and no air oxidation treatment was performed. The specific surface area, electrical conductivity, and oxygen content of the obtained activated carbon are shown in Table 1.

The physical properties of the activated carbons obtained in Examples 1 to 7 and Comparative Examples 1 to 5 are summarized in Table 1.

    (Inspection)    

Using the activated carbons obtained in Examples 1 to 7 and Comparative Examples 1 to 5, the palladium-loaded activated carbon was produced according to the following method of palladium loading. Then, the palladium loading amount, the palladium dispersion degree, and the nitrobenzene hydrogenation performance of the produced palladium-supported activated carbon were measured according to the following methods. The obtained results are shown in Table 2.

    [Production of activated carbon with palladium]    

The activated carbon of each Example and each comparative example was pulverized, and it was set as powder activated carbon. 1 g of powdered activated carbon was added to 20 ml of ion-exchanged water to prepare a slurry. On the other hand, 0.0168 g of palladium chloride was dissolved in 20 ml of 0.1 N hydrochloric acid, and then a 1 N sodium hydroxide solution was added to adjust the pH to about 3.8 to 4.2. While stirring the activated carbon slurry solution, a pH-adjusted palladium chloride solution was added and stirred for 15 minutes. Then, a 10% saturated solution of sodium bicarbonate was added to adjust the pH of the solution to 7, and the mixture was further stirred for 1 hour. Thereafter, 0.8 g of a 37% formic acid solution was added, and refluxed at 100 ° C. for 5 hours in an oil bath to reduce palladium. After the reduction, the catalyst was filtered by a suction filter and thoroughly washed with ion-exchanged water. After washing, vacuum drying was performed at 120 ° C to obtain activated carbon loaded with palladium.

    [Determination of palladium loading of activated carbon loaded with palladium]    

The palladium-containing activated carbon of each of the examples and comparative examples obtained above was vacuum-dried at 120 ° C for 2 hours, and then 0.1 g was added to a decomposition vessel, and 10 ml of 60% nitric acid was added and mixed. A microwave sample pretreatment device was used. (CEM company, DiscoverSP-D80), dissolve the sample. This dissolved solution was taken out, diluted to 25 ml in a graduated cylinder, and the measurement solution was prepared, and then analyzed by an ICP emission spectrophotometer (manufactured by Shimadzu Corporation, ICPE-9800). From the calibration curve prepared from the obtained value and a palladium standard solution of known concentration, the palladium loading was determined.

    [Determination of palladium dispersion of activated carbon loaded with palladium]    

The degree of palladium dispersion was measured by the CO pulse method using Bel-CATII manufactured by MicrotracBEL Co., Ltd. The measurement container made of quartz was filled with the activated carbon containing palladium of each Example and each comparative example, and it installed in the apparatus. Use the following steps for pre-processing. Helium gas was allowed to flow at 50 mL / minute, and the temperature was raised to 100 ° C. at a temperature rise rate of 5 ° C./minute and held for 15 minutes. Thereafter, a reduction treatment was performed by circulating hydrogen gas at 50 mL / min for 20 minutes. After the reduction treatment, helium gas was again flowed at 50 mL / min, and the temperature was cooled to 50 ° C. in the measurement container. After pretreatment, CO pulse measurement was performed. 10% CO / He was used for the adsorbed gas, and the amount of CO adsorbed was measured at a measurement temperature of 50 ° C. The palladium dispersion degree of the palladium-supported activated carbon was measured from the obtained CO adsorption amount and the palladium loading amount calculated by ICP measurement.

    [Determination of hydrogenation performance of nitrobenzene]    

The evaluation was performed using a medium-pressure reduction device "CH-200" manufactured by Ishii Rika Co., Ltd. In a reaction vessel, 4.2 ml of nitrobenzene and 25 ml of 2-propanol were added and mixed, and 50 mg of palladium-containing activated carbon of each of the Examples and Comparative Examples obtained above were added and dispersed in the solution. The reaction vessel was placed in the apparatus, and the vessel was sufficiently replaced with hydrogen, and then the temperature was raised to 40 ° C. After stirring for 15 minutes for stabilization, hydrogen gas having an initial pressure of 0.35 MPa was introduced, and the change in hydrogen pressure in the reaction vessel with time was measured to evaluate the hydrogenation performance. The amount of hydrogen pressure change from the initial hydrogen pressure after 20 minutes of the reaction was read, and the value divided by the specific surface area of the activated carbon was compared. In this embodiment, the value of 1.7E-05 or more is regarded as acceptable.

    (Inspection)    

From the results in Table 2, it is clear that when the activated carbon obtained in Comparative Examples 1 to 5 was used as a palladium support, the amount of change in hydrogen pressure with respect to the specific surface area during the first 20 minutes of the reaction was small.

In contrast to this, if the activated carbon obtained in Examples 1 to 7 is used as a palladium support, although the palladium dispersion degree is the same, it is clear that the hydrogen pressure change amount in the initial 20 minutes of the reaction relative to the specific surface area is increased. , And the hydrogenation performance in the surface area is improved.

This application is based on Japanese Patent Application No. 2017-247439, filed on December 25, 2017, and its contents are included in this application.

In order to present the present invention, while referring to specific examples and the like, the present invention will be appropriately and fully explained through embodiments. However, as long as it is a person with ordinary knowledge in the technical field, he or she can recognize that it can be easily changed and / or The aforementioned embodiment is improved. Therefore, as long as the form of change or improvement implemented by a person having ordinary knowledge in the technical field does not depart from the scope of rights described in the claims of the scope of patent application, the form of change or improvement is to be interpreted as including To the scope of the claim.

    [Industrial availability]    

The present invention has a wide range of industrial applicability in the technical fields of activated carbon or activated carbon on which a catalyst is used.

Claims (5)

    An activated carbon having a conductivity of 3.5 S / cm or more and a oxygen content of 3.0% by mass or more as measured by powder resistance measured at a load of 12 kN.         The activated carbon of claim 1, wherein the activated carbon is derived from coconut shell.         A metal-laden activated carbon is a metal-laden activated carbon as claimed in claim 1.         A metal-laden activated carbon as claimed in claim 3, wherein the metal is palladium.         A hydrogenation catalyst using a metal-laden activated carbon as claimed in claim 3 or 4.